Sophie: scid-3.6.1-6mdv2008.1 x86

scid-3.6.1-6mdv2008.1.x86_64.rpm

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Scid Help: 
Tablebases
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<h1>Tablebases</h1>

<p>
A <b><i><font color="#990000">tablebase</font></i></b> is a file containing the perfect result
information about all positions of a particular material setup,
such as King and Rook versus King and Pawn. Tablebases for all
material situations up to five men (including the Kings) have been
generated, and some simple 6-men tablebases are also available.
</p>
<p>
Scid can use Nalimov-format tablebases that are used by many modern
chess engines. These often end with the file suffix <b>.nbw.emd</b>
or <b>.nbb.emd</b>. All 3-, 4- and 5-men Nalimov tablebases can be
used in Scid.
</p>

<h3>Using tablebases in Scid</h3>
<p>
To use tablebase files in Scid, simply set their directories by
selecting <b>Tablebase directory...</b> from the <b><font color="#007000">[Options]</font></b> menu.
You can select up to 4 directories where your tablebase files are stored.
You can press a <b>...</b> button to the right of an entry to choose a
file, to specify that the directory of that file should be used.
</p>
<p>
When a position found in a tablebase file is reached, the game information
area (below the chessboard) will show tablebase information. You can
configure the amount of information shown by clicking the right-mouse
button in that area or selecting <b>Game information</b> from the
<b><font color="#007000">[Options]</font></b> menu. Selecting the "result and best moves" option
gives the most useful information, but is much often slower than
the "result only" option.
</p>

<h3>The Tablebase window</h3>
<p>
You can get even more tablebase information about the current position
by opening the <b><i><font color="#990000">Tablebase window</font></i></b> (<b><font color="#007000">[Windows]</font></b> menu,
shortcut: Ctrl+Shift+=). This window shows the result with perfect play
of all legal moves from the current position.
</p>
<p>
The window has two main parts. The summary frame (on the left) shows
which tablebases Scid found on your computer and a summary for each
tablebase. The results frame (on the right) shows optimal results for
all moves from the current position displayed in the main window.
</p>

<h4>The summary frame</h4>
<p>
The top part of the summary frame lets you select a particular
tablebase. Those you have available are shown in blue and unavailable
tablebases are shown in gray, but you can select any tablebase.
The lower part of the summary frame shows summary information for the
selected tablebase. (Not all tablebases have a summary recorded in
Scid yet.)
</p>
<p>
The summary includes the frequency (how many games per million reach a
position with this material, computed from a database of more than
600,000 master-level games), a longest mate for either side, and the
number of mutual (or "reciprocal") zugzwangs. A mutual zugwang is a
position where white to move draws and black to move loses, or where
white to move loses and black to move draws, or where whoever moves
loses.
</p>
<p>
For some tablebases with mutual zugzwangs, the summary also includes
a list of all of the zugwang positions or a selection of them. A full
list for every tablebase is not feasible since some tablebases have
thousands of mutual zugzwangs.
</p>
<p>
You can set up a random position from the selected tablebase by pressing
the <b>Random</b> button.
</p>

<h4>The results frame</h4>
<p>
The results frame is updated whenever the chessboard in the main window
changes. The first line shows how many moves win (+), draw (=), lose (-),
or have an unknown result (?). The rest of the frame gives a more detailed
list of results, ranking them from shortest to longest mates, then draws,
then longest to shortest losses. All distances are to checkmate.
</p>

<h4>The results board</h4>
<p>
In a tablebase position, it is often useful what the tablebase results
would be if all the pieces in the current position were on their
current squares but one particular piece was moved somewhere else.
For example, you may want to determine how close a king has to be to
a passed pawn to win or draw a particular position. In endgame books
this information is often called the <i>winning zone</i> or
<i>drawing zone</i> of a piece in a position.
</p>
<p>
You can find this information in Scid by pressing the button with an
image of a chessboard, to show the <b><i><font color="#990000">results board</font></i></b> in the
tablebase window.
When you press the left mouse button on any piece in this board, a
symbol is drawn in each empty square showing what the tablebase result
would be (with the same side to move as the current main window position)
if the selected piece was on that square.
</p>
<p>
There are five different symbols a square can have:
a white <b>#</b> means White wins;
a black <b>#</b> means Black wins;
a blue <b>=</b> means the position is drawn;
a red <b>X</b> means the position is illegal (because the kings are
adjacent or the side to move is giving check); and
a red <b>?</b> means the result is unknown because the necessary
tablebase file is not available.
</p>

<h3>Obtaining Tablebase files</h3>
<p>
See the <a href="Author.html\#Related">related links</a> section for help on finding
tablebase files on the Internet.
</p>

<p><center><font size=-1>(Updated: Scid 3.4, September 2002)</font></center></p>

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